Is it possible to keep particles orientation relative to the emitter when the emitter is rotated?
You have to check Rotation, to make the particle system uses the dupli object's rotation. Using this setting, particle orientation can be tweaked by rotating the dupli object itself:



Next, give one of the object's local axis as the particle system's initial rotation. This way, any new particle will be oriented to that axis:



Now any new emitted particle will always be correctly oriented: